Sticky
object node

This tool creates an object which takes its transform from the world-space position of a UV point on a polygonal surface. You can then parent another object to the Sticky object to make the object follow the surface.

This is similar to the Rivet tool; however, this tool is more precise since you can attach the sticky anywhere on the surface and you can animate the position as well as the object. For example, you could animate a monkey riding on an elephant’s back while sliding across the surface trying to balance.

The Sticky Object gets its transform from the surface of a polygonal
mesh. The mesh must also have texture coordinates that are used to
determine the parameterization of the polygons.

Sticky Objects may be parented to other sticky objects. In this case
they will parent their 2d UV transformation (both the UV offset and the
rotation). If one parents sticky objects, the Fetch World Transform
should be turned on.

The Sticky Geometry path determines the object to stick to. To stick objects to sticky geometry, you must parent the geometry you want stuck to the Sticky node.

For example to stick a sphere to a grid, make sure the grid has uv texture attributes, create a Sticky Object, set the Sticky Geometry to the grid, and parent the sphere to the Sticky Object.

Parameters

Sticky

Sticky Geometry

The SOP to stick the geometry to.

Attribute

The attribute name of the texture to use for the polygonal
parameterization.

UV

The UV coordinates to evaluate the mesh at.

Rotation

The angle to rotate the local coordinate frame about the surface
normal. It will only take effect when Orient to Surface is on.
However, any other sticky objects parented to this one will
inherit this rotation.

Orient To Surface

Whether the local orientation of the point should be used. The
surface normal is used as the Z axis and the texture’s U axis is
used as the Y axis.

Fetch World Transform

If this is set, the transform of the Sticky Geometry will be
used. If not set, the parent transform of this node will be
used.

Wrap in U/V

When not set, u and v values outside the range will be ignored.
When it is set, they will be wrapped until they lie within the
range.

U/V Range

This is the range of texture space to work within. Geometry
whose texture coordinates lie outside this range will be
ignored.

Assume UV Coordinates Unchanging

The sticky object builds a cache of the target surface’s
texture coordinates. When this is set, the cache is kept even if
the target’s geometry changes.

Clear UV Caches

The Sticky Object is conservative about rebuilding the UV
information. This will force it to update the UV texture
lookups.

Render

Display

Whether or not this object is displayed in the viewport and rendered.
Turn on the checkbox to have Houdini use this parameter,
then set the value to 0 to hide the object in the viewport and not render it,
or 1 to show and render the object.
If the checkbox is off, Houdini ignores the value.

Set Wireframe Color

Use the specified wireframe color

Wireframe Color

The display color of the object

Viewport Selecting Enabled

Object is capable of being picked in the viewport.

Select Script

Script to run when the object is picked in the viewport. See
select scripts .

Cache Object Transform

Caches object transforms once Houdini calculates them. This is
especially useful for objects whose world space position is
expensive to calculate (such as Sticky objects),
and objects at the end of long parenting chains (such as
Bones). This option is turned on by default for Sticky and
Bone objects.

See the OBJ Caching section of the
Houdini Preferences window
for how to control the size of the object transform cache.

Geometry Scale

Uniform scaling about the xyz axes.

Display

Whether to display only the icon, only the axis, or both.

Icon

Displays only the icon geometry.

Axis

Displays only the axis.

Icon and Axis

Displays both the icon and axis.

Control Type

Switches between the type of geometry to display.

Null

Displays null geometry (i.e. cross).

Circles

Displays circle primitives.

Box

Displays box primitive.

Planes

Displays plane primitives.

Null and Circles

Displays null and circle primitives.

Null and Box

Displays null and box primitives.

Null and Planes

Displays null and plane primitives.

Custom

If an input source is specified, this option will
display the geometry of the input.

Orientation

Used in conjunction with circle or plane primitives.
Determines which circles or planes to display.

All planes

Displays circle or plane primitives on the YZ, ZX and XY
planes.

YZ plane

Displays a circle or plane primitive on the YZ plane.

ZX plane

Displays a circle or plane primitive on the ZX plane.

XY plane

Displays a circle or plane primitive on the XY plane.

YZ, ZX planes

Displays circle or plane primitives on the YZ and ZX
planes.

YZ, XY planes

Displays circle or plane primitives on the YZ and XY
planes.

ZX, XY planes

Displays circle or plane primitives on the ZX and XY
planes.

Shaded Mode

Determines whether to display the primitives as shaded
objects or as wireframe objects.